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|
#! /usr/bin/env gforth
\ Challenge 100
\
\ TASK #1 > Fun Time
\ Submitted by: Mohammad S Anwar
\ You are given a time (12 hour / 24 hour).
\
\ Write a script to convert the given time from 12 hour format to 24 hour format and vice versa.
\
\ Ideally we expect a one-liner.
\
\ Example 1:
\ Input: 05:15 pm or 05:15pm
\ Output: 17:15
\ Example 2:
\ Input: 19:15
\ Output: 07:15 pm or 07:15pm
\ skip blanks
: skip-blanks ( str len -- str len )
BEGIN
DUP 0= IF EXIT THEN \ string empty
OVER C@ BL <> IF EXIT THEN \ not space
1 /STRING
AGAIN
;
\ parse a time string, return number of minutes since midnight
\ and true if it was in AM/PM format
: parse-time { str len -- hours minutes f-am-pm }
0 0 { hours minutes }
0 0 str len >NUMBER TO len TO str DROP TO hours \ convert hours
str C@ ':' <> IF 1 THROW THEN
str len 1 /STRING TO len TO str \ skip ':'
0 0 str len >NUMBER TO len TO str DROP TO minutes \ convert minutes
str len skip-blanks TO len TO str \ spaces
len 0= IF
hours minutes FALSE
ELSE str C@ DUP 'a' = SWAP 'A' = OR IF \ AM
hours 12 = IF 0 TO hours THEN
hours minutes TRUE
ELSE str C@ DUP 'p' = SWAP 'P' = OR IF \ PM
hours 12 <> IF hours 12 + TO hours THEN
hours minutes TRUE
THEN THEN THEN
;
\ output in 24-hour format
: print24 ( hours minutes -- )
SWAP 100 * + 0 \ convert to hhmm in decimal, double
<# # # ':' HOLD # # #> TYPE
;
\ output in 12-hour format
: print12 { hours minutes -- }
FALSE { pm } \ assume AM
hours DUP 12 > IF
DROP hours 12 - TO hours TRUE TO pm ELSE
DUP 12 = IF
DROP TRUE TO pm ELSE
DUP 0= IF
DROP 12 TO HOURS
ELSE DROP THEN THEN THEN
hours minutes print24
pm IF ." pm" ELSE ." am" THEN
;
\ convert time
: convert-time ( str len -- )
parse-time IF print24 ELSE print12 THEN
;
\ main
NEXT-ARG convert-time CR BYE
|
